Human Depopulation Does Not Yield Automatic Biodiversity Gains in Semi-Natural Ecosystems

Kei Uchida, Tokyo City University
Peter Matanle, University of Sheffield
Yang Li, University of Sheffield
Taku Fujita, The Nature Conservation Society of Japan
Masayoshi Hiraiwa , Kindai University

In recent decades, earth’s ecosystems have been facing collapse. Global studies consistently demonstrate a direct relationship between human population growth and economic expansion, and the resulting habitat destruction and species loss. Meanwhile, developed countries are experiencing below-replacement fertility rates and beginning to depopulate. Many scientists and citizens believe that depopulation will automatically lead to environmentally restorative outcomes. But is this true for biodiversity restoration? To answer this, we must examine the relationship between human depopulation and biodiversity restoration. Using UN data, we identified Japan as the Depopulation Vanguard Country for Northeast Asia, and we analyzed biodiversity change in Japan’s semi-natural areas, considering factors such as population dynamics, land use, and surface temperature. Our findings reveal that, regardless of whether human populations increase or decrease, habitat and biodiversity losses continue, with some species declining more sharply under depopulation. This trend is primarily driven by changes in agricultural land use, whether through urbanization, disuse and abandonment, or intensification. Only in areas where human populations remain more stable does biodiversity appear to be more sustainable. We conclude by urging depopulating countries to adopt land-use policies that consider the potential impacts of depopulation within active biodiversity conservation and restoration strategies.

Keywords: Population, Environment, and Climate Change, Data visualisation

See extended abstract.